There are three major types of implants commonly used for breast enlargement surgeries: a) saline filled or inflatable breast implants, b) saline pre-filled implants, and c) silicone gel pre-filled implants (also called pre-shaped breast enlargement implants). Saline filled breast implants are constructed from room temperature vulcanized (RTV) silicone elastomer, made of polydimethylsiloxane. Silicone gel pre-filled implants are pre-filled by silicone gel and sealed by a manufacturer.
A breast implant's shell is not a monolithic monolayer; rather, it is made up from several layers of “hardening” silicone. Thickness of the shell is measured in “deeps”, which refers to the number of times the process is repeated. An average breast implant is between 4 and 6 “deeps” thick.
Accordingly, the technology used to prepare implants results in a multilayered shell's structure. Further, each layer is not evenly “deep” throughout different parts of the implant's surface. The implantation process involves putting pressure on the implant's shell, causing its distention and deformation. As a result, microseparations may form in the layers, weakening the whole shell's structure. The microseparations also decrease the resistance of the implant's shell to hydrostatic pressure and to the gravity force. Over time, this may result in the penetration of silicone through the implant's shell (“bleeding”) and may increase the potential for disruption and/or leakage.
There is a lot of potential for damage to the implant during its placement into a patient's body. There are four different access incision sites for breast enlargement surgeries: inframammary, transareolar, transaxillary, and transumbilical incisions. Inframammary, transareolar, and transaxillary incisions are used to place saline inflatable and saline and silicone filled pre-shaped implants. Saline inflatable implants are commonly filled with a sterile 0.9% sodium chloride solution either inside or outside the patient's body. Silicone filled implants are filled to a certain volume and sealed by manufacturer.
Transumbilical incision is a less common technique, where an incision is made on the rim of the navel. A tunnel is then made under the skin through the subcutaneous fat layer. An endoscope can be used to create the tunnel and to provide visibility to the surgeon. The tunnel reaches all the way beneath the mammary gland into the layer of tissue in between the breast and pectoral muscles. After a pocket is created under the breast, the implant is inserted through the incision and moved up into the breast area. The implant is then centered behind the nipple. This approach enables implants to be placed with no visible scars on the breast, but makes appropriate dissection and implant placement more difficult. This technique is not appropriate for placing silicone gel and saline pre-filled implants due to potential damage of the implant shell during blunt insertion and long and narrow passage.
There are two primary anatomical positions for permanent placement of breast implants in the body: subglandular and subpectoral. In subglandular breast implant placement, the implants are placed behind the mammary gland and over the chest wall muscles (pectoral major, pectoral minor muscles and pectoral fascia). In subpectoral implant placement, the implants are placed beneath the breast glands and under the chest wall muscles, and anterior to the rib cage. In either method, symmetrical pockets are surgically formed between the described above anatomical structures prior to the placement of any type of breast enlargement implants.
Saline inflatable breast implants are completely deflated outside of the patient's body. When they are inserted in the human body through small skin incisions (about 2.5 to 4.0 cm long), they are rolled in toward the filling valve. Once the deflated implant is placed into the preformed pocket, it is filled with sterile 0.9% sodium chloride solution, up to a designated volume, using one of the preferred breast implants filling kits. The self sealed valve (or plug) is designed to seal the implant's saline content.
Different approaches and techniques are used to place pre-filled saline or silicone filled gel implants. Pre-filled saline or silicone breast implants possess much larger cross sectional dimensions before implantation as compared to deflated inflatable saline implants. Many surgeons prefer to fill inflatable saline implants outside of the patient's body before implantation to observe their shape, size, and to ensure the proper valve closure. Significantly longer skin incisions (from 6.0 cm to 8.0 cm long) and wider dissection of the local tissue are needed to accommodate the passage of pre-filled breast implants and their implantation.
Surgical retractors, for example, Army/Navy or Deaver-type retractors are commonly used to provide incision opening and directional passage for the implant's placement. In the process of placement, a surgeon positions the pre-filled breast implant next to the incision site and then pushes one of the implant's edges inside the retracted incision, while holding the “body” of the implant outside of the incision, preventing it from slipping out of the incision and reassuring the mono-directional movement of the implant into the placement pocket. Usually, the first assistant is keeping the incision site retracted as much as possible, and thus prevents the collapse of the formed placement pocket. During this process, the surgeon places a lot of pressure on the implant to force it into the placement pocket, protruding its mass up to 4.0 to 6.0 cm deep, repeating the process multiple times until all of the implant is successfully placed inside. This implantation method causes a great deal of destructive stress and distention on the implant's shell layers, weakening the shell layers integrity.
The transareolar incision results in scars which are more cosmetically acceptable but it limits the skin incision's length. However, the implant is under a lot of stress when this technique is used. The tissue at the incision area is more resistant to dissections. Further, the implant's passing tunnel has a complex, angled pattern. Thus, transareolar access requires applying more pressure on the shaped implant and creating more local tissue dissections in the process of placement.
The placement of the pre-filled implant through the transaxillary incision is even more complex. The initial part of the implantation tunnel passes under the thickest part of the pectoral major muscle, and the implantation passage has an oblique, caudal, and medially directed path. The incision length is limited by the length of axillary folds. Army/Navy type or Deaver-type retractors are commonly used to maintain a sufficient perimeter of the incision and prevent collapse of the passage. The pre-tilled breast implants are under the pressure from the surgeon's manipulations directed to advance forward segments of the implant, and resistance of the local tissue and anatomical structures. Thus, the process of implant's placement is rather complicated. When the implant is pushed and compressed to force a part of it go inside of the incision or implantation passage, distention of the shell's capsule occurs.
Further, there is a lot of air trapped inside the placement pocket. This air becomes progressively compressed as the implant advances toward the placement pocket, and the air pressure inside the passage rapidly increases. The compressed air resists the implant's advancement and forces the surgeon to apply extra force to overcome the air's resistance. The mechanical pressure resulting from the surgeon's protruding the implant further damages the implant's shell layers and weakens the layers' integrity.
Currently known retractors commonly used in breast enhancement surgeries result in unbalanced and uneven physical pressure, which contributes to the implant's damage during the surgery. Unbalanced physical pressure, applied to the local anatomical structures, causes trauma to the local fat tissue, muscle fibers, nerve endings, lymphatic, and milk ducts, and results in more pain after the surgery, contribute to development of excessive scar formation, and capsule contraction.
Some of the conventional approaches to overcoming these problems involve increasing the incisions' length and making more and wider local tissue dissections along the implantation passage. However, these approaches are themselves deficient since longer incisions and more local tissue dissections are leading to intra operational and post surgical complications such as bleeding, local fat necrosis, breast itself and nipple's lack of sensation, skin irregularities, slow healing, explantations, infection, capsule contraction, and keloid formation.
Accordingly, it would be desirable to provide improved techniques of performing breast implantations by pre-filled implants. It would also be desirable to provide new and improved surgical instruments, such as new and improved retractors.